Stove with imperforate fire pot



2 Sheets-Sheet 1 NTOR.

QI I T m W/lllllldzll ll d/ !lw L w. n lllllllyllllllll 45 INVE I It If v April 5, 1949. J. HARRINGTON STOVE WITH IMPERFORATE FIRE POT Filed April 25, 1942 April 5, 1949.

Filed April 25, 1942 J. HARRINGTON 2,466,170

STOVE WITH IMPERFORA'I'E FIRE POT 2 Sheets-Sheet 2 1v INVENTOR! Emiiliil Min m wm 7M0 ays" Patented Apr. 5, 1949 UNITED STATES PATENT OFFICE 2 Claims.

This invention relates to house heating stoves. Among the objects of the invention are to provide a heating device which in every respect resembles the standard house heating stove and which can be operated by natural draft shovel fire methods, like all other stoves, but in addition thereto it is equipped with a mechanical coal feeding device, a mechanical ash extracting device and a means for stimulating the flow of air to be heated around and in contact with the heating surfaces of the stove for increasing the capacity thereof.

In addition, other objects of the invention are to provide a fire pot of such shape that the heat liberating surface of the fuel bed therein may be expanded or contracted by simply thickening or thinning or increasing or decreasing the thickness 7 of the fire.

Another object is to provide a stove having a fire pot in the form of an inverted cone so that the cross-section thereof at any elevation increases as the square of the depth. In other words, if the fire has a certain area and the thickness thereof is then cut in two, the area or surface of the fuel bed is reduced to one-fourth. The object of this is to maintain a rate of combustion in excess of the critical rate.

Another object of this invention is to provide a stove that will contract the surface area in order to maintain the critical rate of combustion with low quantities of fuel per hour being consumed.

Still another object of this invention is to provide a stove having means set by the operator for adjusting the rate of fuel and ash extraction whereby to carry a thin low fire or a high full fire.

Another object of the invention is to provide a stove of the foregoing principles wherein the fuel is supplied in a large number of small increments per unit of time so that the fuel fed during any one unit of time which may be a minute or an hour or any unit of time, will be so small that the smoke forming gases evolved from such increment is so small that the volatiles will all be consumed within the furnace volume provided and therefore smokelessness and efiiciency will be obtained.

Still another object of the invention is to provide a fuel bed having a hollow or depressed center.

The stove of the present invention by virtue of the plurality of peripheral disposed fuel feeding means deposits the fuel at peripherally disposed points whereby to pile up the coal at a point directly below the fuel feeding means and the coarser coal running down to the center of the fuel bed into the depressed portion. The effect of this action is to provide a fuel bed, the center of which is composed of the coarser particles of the coal and thereby have a greater porosity or less resistance to the fiow of the combustion air. This in turn causes the combustion air following the path of least resistance to flow up through the center of the fuel bed stimulating the combustion in the central area and providing a rate of combustion in said area that will be sufficiently great to provide the necessary temperature for complete combustion of the volatiles.

This being a mechanically fed stove, it is desirable to shut off this unauthorized air during the rest or quiescent period when little heat is desired in order to prevent the burning down and rapid consumption of the coal in the fire. This prolongs the period between firings and is a desirable operating detail.

To provide these and other objects of the invention as will be apparent from a perusal of the following specification when taken in connection with the accompanying drawings, wherein:

Figure l is a perspective View of the device.

Figure 2 is a partial plan sectional view taken on line 2--2 of Figure 1.

Figure 3 is a plan sectional view taken on the line 33 of Figure 1.

Figure 4 is a fragmentary plan sectional view taken on the line 44 of Figure 5.

Figure 5 is a detail view of a driving connection for the device.

Figure 6 is a vertical cross sectional view taken on the line t6 of Figure 1.

Figure 7 is a partial view in vertical cross section of a modified form of structure.

Referring to the drawings in detail, the device, which is selected as an exemplification of the invention, comprises preferably a house heating stove having an outer ornate shell or casing 2 preferably of rectangular construction. This casing is provided with air-introducing louvers 4 at the bottom on one side and headed air louvers 6 at the top thereof. In addition, one of the sides of the casing is provided with an ash cleanout door 8 and a door I!) giving access to combustion chamber door i8.

Within the casing or housing 2 and spaced from the walls thereof so as to provide air passages is disposed a rectangular fire pot I?! which is provided with a depending or lower conical or pyramidal fuel bed supporting section M, which tapers gradually downwardly but at a relatively steep incline with respect to the horizontal to an ash discharge portion 16 which is relatively small in diameter as compared with the length of the axis line of the fuel bed supporting portion.

One of the walls of the fire pot I2 is provided with a door I8 registering with the clean-out door ID. The exterior of the walls of the fire pot l2 and M are provided with heat radiating projections 20. The bottom of the conical section I4 passes through a horizontal partition 22 which is arranged to provide an air passageway around the fire pot.

In addition, there is a vertical partition 24 which joins with the horizontal partition 22, whereby to provide an air conduit on the side containing the louvers 8 so that air passing through the louvers will pass upwardly around an electric motor 26 and its driving connection, at which point the air is diverted horizontally by a partition 3t directly onto the lower portion of the fire pot is. From this point the air flows upwardly around the fire pot and thence across and through passageways 552 formed in the upper portion of the fire pot and thence outwardly through the heated-air discharge louvers ii at the top of the casing. In this manner the cooling air brought into the bottom of the stove is utilized to maintain the-motor cool and then on its passage upwardly through the stove serves first to cool the fire pot and then the air is heated thoroughly and efficiently until it passes upwardly through the discharge louvers 8 into the room to be heated.

Immediately below the ash discharge mouth liiof the conical fire pot there is disposed a horizontally rotatable ash discharging mechanism 3 5 provided with a series of curved ribs on its upper surface for ash discharging purposes, which ribs will, when rotated, serve to throw the ash outwardly from the center of the rotating plate. These ribs 34 are rotatably mounted on a vertical axis 36 and ar provided on their undersurface with teeth 38 which are driven by means of a pinion All on a shaft 32 carried by any suitable mountings M. This shaft 2 at its outer end projects through the partition 24 and is provided with a ratchet Wheel (see Figure 5) which is actuated by means of a pawl 50 pivoted at 5 2 on a link 5%, having a series of adjusting holes 56. The outer end of this link is connected to a pivoted rod 53 which is in turn connected to a crank 86 on the gear reducer 52. This gear reducer is driven by means of a belt 6 3 from the motor 26.

In addition, the motor 26 is provided with a fan 66 which is adapted to blow the fresh incoming air onto the lower conical portion of the fire pot 14 whereby to keep it cool. In addition, this fan serves to draw in the fresh air from the louvers d.

The motor is controlled by a room thermostat 68 suitably connected by wiring iii to the motor, whereby the motor is stopped or started automatically in accordanc with the room temperature.

The upper portion of the fire pot is provided with a plurality of upstanding passages #2, there being three shown which connect with the cross discharge pipe or header i l in turn connecting to the combustion-gas discharge pipe or stack 16 leading to the outside of the housing for discharging the heated products of combustion therefrom.

It will be noted that the spaces between these upstanding passages i2 provide hollow air passages 32 through which the air being heated passes on its way to the hot air discharge louvers 6.

In addition, the fire pot is provided with fuel feeding chambers 18 disposed on two opposite sides thereof, as shown clearly in Figures 3 and,

6. These chambers are of substantially rectangular formation and have suitably tapered bottom walls so as to divert the fuel, such as coal. These fuel chambers are arranged so as to provide a central ridge to which will provide a sloping face 82 sloping toward the cylindrical toothed feed Wheel 84 and a sloping face 86 sloping toward the oppositely disposed feed wheel 88.

In addition, there is provided a sloping face 91! which slopes toward the feed wheel 34 and a sloping face 92 which slopes downwardly toward the feed wheel 8:2, thereby providing three downwardly sloping surfaces all of which slope toward the feed wheel 8 which feeding device is disposed in an opening til at the top of the vertical inner wall of the rectangular portion of the fire pot l2. There are two such fuel feeding magazines, one on each side, identically constructed. Each one of the fuel feeding wheels lit and 88 is provided with teeth forming feeding surfaces when the wheel is rotated in the proper direction so as to feed the fuel from the bottom of each hopper into the fire pot. Inasinuch as there are four of these wheels, one arranged at each corner of the fire pot, the fuel will be fed simultaneously preferably alternately from the four corners into the fire pot. Any suitable means for operating the fuel feeding devices may be utilized.

In the present instance each one is driven by a ratchet wheel cu in turn operated a pawl is pivotally mounted upon a lever ill-t pivoted on the axis of the ratchet. The outer end of the lever iilii is provided with adjustment holes I32 to receive the upper end of the rod whereby upon reciprocation of the rod 58 the link ill?) will be oscillated to rotate the two ratchet wheels on the shaft ltd, which is the shaft on which the two feed wheels 84 and 88 are mounted. The

outer end ist of this shaft projects outwardly through the casing 2 to receive a handle it. This handle is normally maintained on the outer squared end of the shaft 42 but may be detached therefrom to apply it to the end 586 if desired.

The opposed pair of feed wheels 84 and 88 mounted upon the other shaft W5 are driven from the first mentioned feed wheel mechanism by means of a link H0 pivotally connected as at l l2 to a link I M, which is actuated by the ratchet shaft Hit. The link I I0 pivotally connects with a similar link I I6, which in turn is connected to the opposite shaft I95, said shaft also supporting the ratchet wheel 84.

In addition, there is provided the link H8 carrying the pawl I20 for operating these two feed wheels in alternation to the actuation of the opposite feed wheels. In short, upon reciprocation of the rod 58, the ratchets on one side will operate the feed wheels ina clockwise direction to cause the feeding of the fuel into the fire pot. During this clockwise movement the ratchets on the opposite feed wheels will be moved clockwise to positions to engage new ratchet teeth and then upon the reverse rotation of these ratchet teeth will be moved counterclockwise by the pawl to feed the fuel downwardly on the opposite side of I the rectangular portion of the fire pot.

Thus, the four feed Wheels in pairs operate alternately to impart a continuous relatively slow feed of the fuel from the four corners of the rectanguar feed pot toward the center.

B reference to the dotted lines in Figure 6, it will be noted that due to the conical construction of the lower portion of the fuel pot, the fuel bed becomes smaller in cross sectional area from top to bottom, that is, there is provided a conical fire pot which provides for reduction of the fuel bed surface in accordance with the depth of the fuel bed.

So also it is to be noted that by synchronizing the operating means for feedingthe fuel into the.

fire pot in conjunction with the rotation of the ash-receiving plate 34, there is provided means for synchronizing the ash removal and the fuel feed, which in turn is governed by the thermostat means within the room being heated.

In addition, there is also provided a variable discharge of ash in proportion to the amount of ash disposed per unit time by variation in the speed of the rotation of the ash-supporting plate. So also, the coal is automatically fed to the furnace and the ash is continuously and automatically removed. The variability in the amount of the coal fed is a function of the position of the connecting rod in the arm and the lever Hill, which give a greater or lesser angular throw, and the adjustment is on one side only. The two levers, the one operating the fuel feed and the other operating the ash removal, are synchronized in accordance with the amount of ash in the fuel being burned.

Thus, in Figure 5, adjustment may be made for the amount of ash to be discharged, to correspond with the particular amount of ash in the fuel being fed. By having the adjustment shown in Figure 5 as well as the adjustments i622 shown in Figure 6, any desired rate of fuel feed relative to the ash discharge may be provided.

Means is provided to automatically substantially close the ash pit to the admission of combustion air during the off or rest period in which reduced amounts of heat are desired. To this end there is provided a vane i122 placed in front of the circulating fan 66 in such manner that the air impinging upon the vane I22 will deflect it to an inclined position. This vane E22 is connected by suitable links and levers to another damper I24 which closes the air admission opening to the ash pit. The mechanism is suitably constructed so that when the air blast from fan 65 is stopped the damper l24 will automatically close, shutting off the combustion air. The moment the fan starts, however, the vane 522 is deflected to an inclined position and the damper I24 is opened and air is admitted.

In addition, means is provided for preventing the over-filling of the fire pot should the fuel feeding mechanism be adjusted so as to feed more coal than can be consumed. In the present invention this is carried out by means of a preferably pendant vane l25 suspended from a pivotally supported shaft !28 located at an upper edge of said vane and passing through the side walls of the upper portion of the fire pot Hi. In addition, a mercury switch I2? is fastened to the outer end of this shaft in such a manner that when the vane I26 is deflected from the perpendicular position the mercury switch will be tilted and electric contact broken. This stops the fuel feeding motor and consequent fuel feeding. In order to accommodate the lateral movement of this vane E25 the upper wall portion of the fire pot M is projected outwardly of the adjacent upper portion of the vertical wall of the fire pot so that space is provided for the vane when angularly deflected. Whenever the fuel feed exceeds the rate of combustion the depth of the fuel bed will increase until the bottom edge of the vane I26 is reached. Any further fuel feed will cause the coal to pile up against the vane I28 and push it backwardly or outwardly into the space provided by the recessed inside wall of the fire pot whereby to stop the fuel feeding.

Means is provided for preventing the bridging over of the ash bed at the bottom of the conical fire pot and thereby preventing the free flow therefrom to the central portion of the ash extracting device. To this end a stirrer I30 is attached to the rotatable ash extractor which stirrer projects through the orifice of the cone l4 and extends upwardly along and adjacent to the side of the cone. This stirrer rotates slowly with the ash removing ribs and by such movement prevents the formation of an arch which would prevent the flow of ashes downwardly.

Thus it will be seen that the stove embraces the following advantages; first, due to the formation of a concave fuel bed wherein the concavity faces upwardly, the concave portion provides a relatively more porous burning portion of the bed than the peripheral portions of the bed. This concave fuel bed results from the peripheral coal feeding and the downwardly converging wall portions I l. The new coal is fed in at peripheral portions of the concave firepot and preferably at spaced apart peripheral portions in such a manher that the finer cut portions of the fresh coal are disposed at the periphery of the bed and the larger pieces of the coal, by gravitational action, roll or move down inclined portions of the fuel bed onto the lower concave central porous portions of the bed whereby there is produced a greater porosity through the center of the bed, due to this portion of the fire being composed of the coarser portions of the coal.

The results achieved from this are a certain concentration of draft at this point, producing a rather localized intensity of burning, it being a fundamental principle of this design that the temperature of the fuel bed must be kept above the ignition temperature of the volatiles in the coal for'the purpose of burning such volatiles immediately upon their release from the fuel. It is essential that a definite localization of draft be secured for this purpose.

It is fundamental that the temperature at and near the surface of a fuel bed is a function of the rate of burning per unit of area per unit of time. In other words, a concentration of the draft stimulating the rate of combustion at the central portion of the fuel bed will produce a sufficiently high fuel bed temperature to consume the gases as they are evolved.

The conical or pyramidal shape of the fire pot produces a contraction of area in proportion to the thickness or depth of the fire. As the fire is thinned out and becomes lower, it automatically contracts in area and the rate of burning per unit of area of fuel surface is thereby increased. Where a small fire is wanted, little fuel is used, and the fire is lowered. Where a large fire is wanted, a greater quantity of fuel is put in. This is new.

The ash extraction turn table means at the bottom is simple and has practical value in that it allows large incombustible material to be rejected, which would be impossible in the case of previous devices.

for air, the finer portions pass through only, "and the clinkers accumulate on the grate and have to be periodically removed by hand or by tilting the grate, which is a dirty, disagreeable job. The plate 38 rotates very slowly of the order of one revolution per hour. Coal" goes in at the top with, say, 10 per cent of ash, and the volume of ash coming out at the bottom is only 10 per cent of the volume of the coal, so necessarily the revolutions of the turn table are very slow.

The table in the instant device is supplied with a central cone and a series of ribs, that is, a central cone with tangential ribs running from In an ordinary stove, wherein the grate consists of a series of bars spaced apart the periphery of, the cone to the periphery of the:;plate-. The ash is cammed off. The ashis swept out by the vanes which are so disposed that the rotation of the plate will automatically carry or'push the ash to the periphery of the ash'plate.

Oneof the important features is the provision of a conical or pyramidal faced fuel bed with the smaller end lowermost whereby the horizontal cross-sectional area of the fuel bed automatically' contracts or expands in direct proportion to theamount of fuel fed where the fuel is continuously or substantially continuously fed; that is, in the present instance, the periodic increments are so relatively short that the effect is substantiallya continuous feed. The fuel feed, ash removal and draft are all harmonized to a certain rate of burning and the fuel bed r mains in balance, which is to say that the coal fed equals the coal consumed and the ash removal corresponds with the amount of ash deposited. The: foregoing can only happen in case of a uniform,

and continuous stoking. Therefore the present device combines the advantages of a relatively cheap house heating stove having means for mechanically stoking the same which means the continuous automatic feed of the coal and the continuous automatic extraction of the ash at:

rates in harmony With each other whereby to provide and maintain a constant balanced conditionof the fuel bed; that is to say, a fuel bed always in the same condition as to thickness and rate of burning.

Furthermore, in the present device there is no forced draft taken in the ordinary sense. There is a natural draft in the fuel bed and a pressure in the furnace of less than atmospheric. This is natural chimney draft.

It is to be understood that in the claims the expression downwardly converging Wall portions as applied to the conical section of the-- lower portion of the fire pot comp-rehends as well a pyramidal section also serving as the fuel bedsuppor-ting portion.

It is possible to secure the ash discharge by supporting the ash on a roll spaced apart fromi thebottom end of the cone in lieu of the horizontal table. used in place of the table, quite similar to thefeed rolls at the bottom of the coal hoppers.

This type ofstructure is illustrated in Figure- 7. Adjacent the -bottom opening it of the fire.

pot l2 there is positioned a discharge roll l36' which supports the ash. The discharge roll I36.

may be actuated periodipally in a manner simi:-

lar to the actuation of the horizontal table 3 described in connection Witrrth embodiment of Figure 6.

A feature which is new in the present invention is the variation of the surface area of therfire secured by varying the deptlhpf the fire measured from the level of the ash discharge ori-- fice. For instance, the area of the surface is" reduced to one fourth of its original size\ wh-en1 the depth is reduced one half so that rapid variationin surface area can be secured by relatively small changes in fuel bed depth. nection, in an ordinary stove there are times of many hours duration when it is desired to reducethe rate of burning :to apractically banked condition in order to produce as little heat as possible in warm weather. It is found in practice: in the ordinary stove that when this rate of burning, in total parts of coal per hour, is reduced beyond a'certain critical amount-thatither In short, a discharge roll may be- In this con- The. following references are of 70';

3? fire simply. 'goes out because the rate, of; burning is soslowthat itdoes notmaintain the-tempera: ture necessary for the continuation of combus-.. tion. In the present invention, however, by reducing thesize of the fire; to, say, one fourth of its original area, it is obvious that the rate;

of burning perhour may be reduced anday et maintain a sufficient rate per unit area that 001117-- bustion will be continuous. Under these condie tions it is only necessary to change the position,

of operating-link 53 so to feed reduced quantitles of coal. The fire then automaticallyburns to a lowerand lower point, constantly contracting-=the size of the fire, or itssurface area. The

;small amount of coal desired to be burned can .ing a fuel-bed supporting portion having a downwardly converging and relatively steep substantially conical imperf-orate wall terminating in an; ash discharge opening the diameter of which is. much smaller than the height of the conical wall, fuel storage means having fuel discharge openings disposed a substantial distance above said fuel-bed supporting portion, fuel feeding devices associated with said fuel discharge openlugs and disposed about the periphery of said fire pot and above said fuel-bed supporting portion for delivering fuel to fall-freely upon-the; peripheral portions of the fuel bed in said fire pot, thereby effecting separation of the coarse, and fine fuel particles, and ash supporting and discharge means disposed below said ash discharge opening.

2; In a, house heating stove, afire pot includ ing a fuel-bed supporting portion'having a downwardly converging and relatively steep substan tially conical imperforate wallterminatingin anv ash discharge opening the diameter of which;is,-: much smaller than the height of the conical wall, 7 fuel storage means having fuel discharge openings disposed a substantial distance above said: fuel-bedsupportingportion, fuel fee-ding devices. associated with said fuel discharge openings and: disposed aboutthe periphery of said fire pot; andi above said fuel-bed supporting portion for-doe l'i-vering fuel to fall freely upon the peripheral portions-of the fuel bed in-said fire pot, thereby effecting separation of the coarse and fine-fuel; particles, and ash supporting and discharge" means below said ash discharge opening and dispsed substantially at the point of convergence. ofthe projected conical Wall.

JOSEPH HARRINGTON.

REFERENCES CITED record, in. the: nle of this patent:

UNITED STATES PATENTS (Other references on following page) Number UNITED STATES PATENTS Name Date Gorton Oct. 29, 1889 Brandt Sept. 13, 1892 5 Cooke Mar. 6, 1894 Long July 31, 1894 Clarkson July 4, 1916 Skinner May 8, 1917 Jackson Oct. 14, 1924 10 Fahnestock Apr. 23, 1929 Number 10 Name Date Strange Jan. 9, 1934 Lauterbur et a1. Aug. 14, 1934 Kelly Aug. 13, 1935 Hunter July 13, 1937 Cruikohank Aug. 24, 1937 Macchi May 24, 1938 Valentine et a1 June 18, 1940 Meyer Sept. 24, 1940 Foulds May 20, 1941 Blouvelt et a1. Oct. 27, 1942 

